Foulden Maar: Difference between revisions

The Foulden Maar crater is approximately {{convert|1000|m|ft}} in diameter; its diatomaceous layer is estimated to be {{convert|200|m|ft}} deep.<ref name=":5">{{Cite journal |last1=Lee |first1=Daphne E. |last2=Kaulfuss |first2=Uwe |last3=Conran |first3=John G. |last4=Bannister |first4=Jennifer M. |last5=Lindqvist |first5=Jon K. |date=1 October 2016 |title=Biodiversity and palaeoecology of Foulden Maar: an early Miocene Konservat-Lagerstätte deposit in southern New Zealand|journal=Alcheringa: An Australasian Journal of Palaeontology |volume=40 |issue=4 |pages=525–541 |doi=10.1080/03115518.2016.1206321 |bibcode=2016Alch...40..525L |s2cid=132004293 |issn=0311-5518}}</ref> The Foulden Maar lake formed in a volcanic crater during the [[Waitakian]] ([[early Miocene]]), approximately 23&nbsp;million years ago.<ref name=":0" /><ref>{{Cite web|url=http://www.fossilworks.org/cgi-bin/bridge.pl?a=collectionSearch&collection_no=50035|title=Fossilworks: Gateway to the Paleobiology Database|website=fossilworks.org|access-date=17 December 2021}}</ref> It was deep and anoxic at the bottom, which precluded decomposition of plant and animal remains. The lake was hydrologically isolated, meaning that no rivers or streams disturbed the sedimentation, which formed multiple laminated layers. These thin layers of silica are known as diatomite, as they are composed primarily of one [[diatom]] species, ''[[Encyonema jordaniforme]]'' Krammer, that grew on submerged rocks or aquatic plants in the lake.<ref name=":7">{{Cite journal |last1=Mildenhall |first1=Dallas C. |last2=Kennedy |first2=Elizabeth M. |last3=Lee |first3=Daphne E. |last4=Kaulfuss |first4=Uwe |last5=Bannister |first5=Jennifer M. |last6=Fox |first6=Bethany |last7=Conran |first7=John G. |date=2014 |title=Palynology of the early Miocene Foulden Maar, Otago, New Zealand: Diversity following destruction |journal=Review of Palaeobotany and Palynology |volume=204 |pages=27–42 |doi=10.1016/j.revpalbo.2014.02.003|bibcode=2014RPaPa.204...27M }}{{Subscription required}}</ref><ref>{{Cite journal |last1=Harper |first1=Margaret A. |last2=Van De Vijver |first2=Bart |last3=Kaulfuss |first3=Uwe |last4=Lee |first4=Daphne E. |date=2019 |title=Resolving the confusion between two fossil freshwater diatoms from Otago, New Zealand: ''Encyonema jordanii'' and ''Encyonema jordaniforme'' (Cymbellaceae, Bacillariophyta) |journal=Phytotaxa |volume=394 |issue=4 |pages=231–243|doi=10.11646/phytotaxa.394.4.1 |s2cid=92579845 |issn=1179-3163 }}</ref> As the lake gradually filled in and dried out, the diatomite layers capture a detailed fossil record of about 130,000 years.<ref name=":6">{{Cite journal|last1=Lindqvist|first1=Jon K.|last2=Lee|first2=Daphne E.|date=1 December 2009|title=High-frequency paleoclimate signals from Foulden Maar, Waipiata Volcanic Field, southern New Zealand: An Early Miocene varved lacustrine diatomite deposit|journal=Sedimentary Geology |language=en |volume=222 |issue=1–2 |pages=98–110 |doi=10.1016/j.sedgeo.2009.07.009|bibcode=2009SedG..222...98L}}</ref>